Nitrogen-containing organosilanes such as alkylaminosilanes or dialkylaminosilanes are used as precursors for depositing, via chemical vapor deposition (CVD) or similar means, silicon nitride, silicon carbonitride, and silicon oxynitride films that can be used in semiconductor device fabrication.
The alkylaminosilanes, for example bis(tertiary-butylamino)silane (BTBAS) and dialkylaminosilanes, for example diethylaminosilane (DEAS) and di-isopropylaminosilane (DIPAS), are representative of liquid phase nitrogen-containing aminosilane chemical precursors and are employed for the chemical vapor deposition (CVD) or plasma enhanced chemical vapor deposition (PECVD) of silicon nitride, silicon oxynitride and silicon dioxide films. The deposited films obtained using BTBAS as the precursor with ammonia, for example, are free of ammonium chloride and chlorine contamination as compared to the films deposited from dichlorosilane (DCS) and ammonia via CVD. And such films can be formed at relatively low process temperatures, i.e., 500 to 600° C. Furthermore, these alkylaminosilanes or dialkylaminosilanes produce films which are substantially free, or contain very low levels, of carbon due to the fact they do not contain direct Si—C bonds.
Oxygen-containing organosilane liquids, for example diethoxymethylsilane, are used for the plasma enhanced chemical vapor deposition of silicon oxide, carbon-doped silicon oxide, porous silicon oxide. The resulting films can be employed as inter-metal layer to avoid cross-talking between copper interconnects.
The nitrogen-containing organosilanes such as BTBAS, DEAS, and DIPAS having either N—H or Si—H fragments or both and certain oxygen-containing organosilanes containing Si—H fragments often are susceptible to decomposition over time resulting in main product degradation. In some cases product decomposition can be 20-450 ppm per day and higher, thereby resulting in a significantly reduced product shelf life. Thus, there is a need in the art for an economic and expedient process to halt and stabilize nitrogen-containing and oxygen-containing organosilanes having a decomposition rate typically of at least 50 ppm/day employed for use in semiconductor applications.
The following patents are representative of the prior arts for producing nitrogen-containing organosilanes or oxygen-containing organosilanes as well as their use in depositing silicon nitride, silicon oxynitride and silicon dioxide films:
U.S. Pat. No. 6,963,006 discloses a process for producing alkylaminosilanes, and BTBAS in particular, by reacting a dichlorosilane with an alkylamine in the absence of a solvent under anhydrous conditions. A liquid comprised of an alkylaminosilane and alkylamine hydrochloride salt is formed. The alkylaminosilane is separated from the alkylamine hydrochloride salt and the alkylaminosilane purified by either atmosphere or vacuum distillation.
U.S. Pat. No. 2,834,648 discloses a process for effecting disproportionation of chlorosilanes employing amine-type catalysts. Particularly suited amines for effecting disproportionation are dialkyl and trialkyl amines.
U.S. Pat. No. 3,928,542 discloses a process for enhancing the ability of solid anion resins to effect disproportionation or redistribution of chlorosilicon hydrides, such as silicon hydrides. In the process an amino ion exchange resin is treated with HCl and the resin employed in the disproportion reaction.
EP 0028524 discloses a process for producing alkoxysilane cluster compounds of the formula:RSi[SiO4]3[R′]9-n[R″]n by reacting an alkoxysilane cluster compound of the formula:RSi[SiO4]3[R′]9 with an alcohol in the presence of an acidic catalyst. Representative catalysts are acidic ion-exchange resins, Lewis acids, acidic alcohols and the like.
EP 0206621 discloses a process for forming mono and dichlorosilanes by disproportionating silanes of the formula R1HmSiX4−(1+m) by contacting a silane having at least one Si—H bond of the formula:R1HmSiX4−(1+m) with a neutralization adduct of a sulfonic acid-type or quaternary ammonium salt-type anion exchange resin catalyst.
U.S. Pat. No. 4,798,889 discloses a method for stabilizing unsaturated organosilicones containing specific vinylic groups in the molecule with the use of a hydroxylamine to reduce thermally induced polymerization.
U.S. Pat. No. 4,709,067 discloses a process for stabilizing methacryloxy and acryloxy organosilicon compounds with the use of a phenolic inhibitor such as MMHQ, aromatic amines or aromatic sulfur compounds in the presence of a platinum catalyst and the presence of small amounts of alcohols during the vacuum distillation.
U.S. Pat. No. 4,368,313 address stabilization of silanol hydrolysates of organosilanes to increase shelf life through the additional of a neutralizing agent containing chelatable metal ions.
U.S. Pat. No. 3,928,542 discloses the preparation of anion exchange resins with dry hydrogen chloride to enhance the ability of the resin to redistribute chlorosilanes.
Aylett and Emsley, The Preparation and Properties of Dimethylamino and Diethylamino Silane, J. Chem. Soc. (A) p 652-655, 1967, disclose the preparation of dimethylamino and diethylaminosilane by the reaction of silane with the respective dialkyl amine.
Anderson and Rankin, Isopropyldisilylamine and disilyl-t-butylamine: Preparation, Spectroscopic Properties, and Molecular Structure in the Gas Phase, Determined by Electron Diffraction, J. Chem. Soc. Dalton Trans., p 779-783 1989 disclose the synthesis of isopropyldisilylamine and disilyl-t-butylamine and provide spectroscopic comparison to the corresponding methyldisilylamine.